Mating Season
by BlueSkyBlue
Summary: Centuries ago, the Kazuko family angered a god who proceeded to curse the family. Since then, members of the Kazuko family and those who are related to them begun to display some snakelike tendencies. Some hibernate during winter while others are overwhelmed by the desire to kill. This curse still exists in some individuals in the present day, including one Shiota Nagisa. YAOI!


**Sooooooo... I had this idea for a very very long time. In fact, I worked on this fic with my best friend two years ago but we just gave up on it because we are people who get easily embarrassed. However, this idea of mine just would not go away so I managed to muster up enough courage to type it out. It certainly is something different compared to When Nagisa Goes MIA.**

 **This will be a twoshot fic. And it most certainly be Yaoi (Karma x Nagisa), so if you guys don't like, please don't read it. Proceed with warning!**

 **With that, I hope you guys enjoy this chapter!**

 **Disclaimer: I do not own Assassination Classroom in any form.**

 **P.S. I need help from someone with writing the next chapter. Even though I am a writer, I am not comfortable with writing smut, and that will be the contents of the next chapter. Writing out some of the scenes that you might read later was already very embarrassing for me. If there are any volunteers, please PM me. Thank you.**

* * *

Long ago, the gods lived close to the humans. In fact, the gods gathered followers among the humans. Asura, the god of good luck, was one of these gods and had many followers. Among Asura's many followers, Asura favored the Kazuko family. Asura guided the Kazuko family with his teachings and helped them achieve wealth, status and popularity with their kind-hearted nature. In return, the Kazuko family offered up many offerings to Asura and were faithful to his teachings. The Kazuko family were admired by everyone around them. However, the gods returned to their dwellings for a long time. As time passed, the descendants of the Kazuko family began to doubt the true power of Asura. They abandoned the teachings of Asura and became arrogant, thinking they were good enough to become the equals of Asura.

For a long time, Asura ignored the lack of offerings of the Kazuko family, thinking that there was a lack of available offerings. Then he noticed the Kazuko family had stopped following his teachings but he dismissed it as his followers being overwhelmed with their daily lives. Asura was patient with the Kazuko family until he accidentally discovered a few men from the Kazuko family trying to destroy one of his altars. Asura was enraged by the Kazuko families betrayal. In his rage, Asura cursed the Kazuko family to possess snake characteristics as the snake was the most feared animal at the time.

Some began hibernating during the winter months...

 _"Mom! Mom!" a little boy gleefully ran up to hug his mother, "Look there's snow outside!"_

 _The lady walked to the window and looked outside with tears in her eyes and answered her son, "Yes. Yes it is, sweetie."_

 _The boy yawned and ran up to give his mother a hug._

 _"It's time for my nap, mom," the boy said with glee, his skin already felt colder._

 _"That's right, dear. Go into the bedroom with the heater," the mother said while holding back her tears._

 _"Ok," said the little boy as he walked into the room and jumped into the bed as his mother walked through the door._

 _"Goodnight, mom! I love you," the boy called out to his mother as she closed the windows and curtains._

 _"Goodnight, sweetie," the mother managed to whisper as she started to cry._

 _"Don't forget to wake me up after winter," the little boy whispered as he shut his eyes._

 _The mother only nodded in agreement as she broke down in sobs next to her little boy's bed._

Other cursed members of the family could only eat their meat raw. These cursed ones die early in life. Who would be able to survive eating only raw meat? Others developed violent tendencies and became controlled by their instinct to kill which made them, of course, serial killers.

 _"Drop everything and put your hands up!" shouted a man as he held a gun up to a businessman's face._

 _The businessman immediately dropped his belongings and raised his hands. He unconsciously shut his eyes in fear. He prepared himself for the inevitable. A loud clattering sound filled the dead silence in the alley where they were. The businessman opened his eyes at the sound to see the gun on the ground near his feet and the man lunging to him with a savage look on his face. The savage man's hands found themselves around the businessman's neck and began to wring the neck, slowly strangling the businessman to death._

Occasionally, the curse would skip over a few lucky generations and they lived happy, uneventful lives. However, the curse of the Kazuko family soon spread to other families through the bloodline of the Kazuko family females that were married off to other families. The first of these was the Kazehaya family, then the Nozomi family, then onto the Nishikino family, followed by the Haninozuka family and the curse just continued to spread. Till this date, the curse still lives in a few unknowing individuals.

* * *

"Mommy?"

Shiota Hiromi looked down at her six-year-old son. "Is there anything wrong?"

The small tealnette made a weird face. "My wee wee feels funny."

She sighed. "Aren't you old enough to go to the potty already?"

"B-But!" The child began to cry. "I-I tried! Nothing came out!"

Hiromi frowned. Her mother senses were telling her that something was not right. Gathering the crying child in her arms, she brought them to her bedroom where she put her child on the bed. She pulled down the tiny trousers around his waist.

And stared.

 _How on earth did a six-year-old boy manage to get an erect dick?_

Somewhere at the back of her mind, she knew that this was not normal. But she tried to help her son in the unexpected situation.

"Okay, listen to me, Nagisa," she held her son tightly. "I want you to take your wee wee and massage it, okay?"

The child followed her instructions, but instantly began to cry again. "I-It hurts!"

The worried mother began to panic. _Something is wrong with her son and she does not know how to deal with it._

Out of options, Hiromi gathered her son in her arms and rushed to get her car keys. She carefully placed the boy on the passenger seat and fastened the seatbelt over his tiny figure. She then got into the driver's seat and started the engine. She needed to get to the hospital, fast.

* * *

Hiromi was a nervous wreck as the man dressed in white gave a look at her. "I have a question."

"Y-Yes?"

"Do you keep Viagra lying around in your house?"

She sputtered. "Wha-? No I don't! And even if I did, I wouldn't put them somewhere where my son will be able to reach! What do you think I am? An idiot?"

The doctor gave her serious look. "Well, whatever this sickness or disease is, your son is the only one who has it. Thus, we have no cure for it. I would advice you help him through this difficult period of time. There is nothing else we can do."

The shocked mother sat still. There was nothing the doctors could do? Then how is she going to help her son with this... unexpected illness?

"We will work and try to figure out something from our side, but there are no guarantees. It would be best if you just take him home."

Nodding, the woman gathered her son into her arms and left the office.

* * *

"Hello? This is Shiota Hiromi, mother of Shiota Nagisa. I'm calling to inform the school that my son is sick and won't be attending school for a while." Hiromi said as she spoke into the receiver.

 _"Okay, would you like any friends of his to pick up his homework?"_

"Oh, I would be coming by every two days to pick up his homework, don't worry."

 _"Alright, I wish Nagisa-kun a speedy recovery."_

"Thank you."

With that, the call ended. The exhausted mother placed the phone beside her as she looked towards her son, who somehow managed to fall asleep in his situation. Once in a while, however, he let out small whimpers as he tossed and turned on the bed.

That night, Hiromi too fell into a restless sleep.

* * *

The illness, or whatever it is, lasted for a week. Throughout the course of the week, Hiromi called in sick from work to take care of her son. She carried the boy to the tub and filled it with cold water, as he had developed a high temperature too. She gave him ice cream and other cold food in hopes of easing her son's pain, but nothing worked.

That week was certainly an extremely exhausting week.

Only after that week did that unnatural erection go away, and Hiromi was relieved. Finally, her son's life would return to normal and he could live the life of a normal child.

Or so she thought.

It happened again the next year.

And the year after the next.

And the following years after that.

Every year around late spring, Nagisa would wake up in bed with a stiff dick. Every year, Hiromi had to call in sick for a week so that she could take care of her son.

Every year she would bring the situation up to the doctors, but they could do nothing to help. They could only speculate. One theory was there was a gene mutation when she was pregnant with Nagisa. Another was that there was something in her house that can cause an unnatural allergic reaction to her son. Hiromi did not believe in any of those theories. She just wanted her son to be _normal_.

Every year, she would have to call the school to inform them about her son's sickness. She would conveniently leave out information on what kind of sickness it was, and instead tell them that he would be sick for a week, and that he would return the week after that.

Every year, she would do her best to take care of her son, though it pains her to see him in the situation over and over again.

But she was just doing her responsibility as a mother: doing her best to raise her child.

However, as her son grew up, she noticed a few things that just felt... _off_ about him. Whenever he smiles, it was as if a snake had coiled itself around her body, threatening to squeeze her to death. There was something about him that screams _snake_.

Hiromi just shrugged off the feeling. It was probably just her imagination.

* * *

Nagisa grew up with a sense of appreciation for his mother. He knew that his mother sacrificed a lot to bring him up. He knew of all the troubles she had to suffer as she took care of him. He remembered the pain he was in every year, and he remembered the dedication she had as she meticulously looked after him.

He remembered the time when he turned thirteen when she presented him with a vibrator and a remote control, explaining to him how it works and how he can relieve himself with it. After that, he used it whenever he fell sick that one week every year. It helped relieve some of his mother's burdens, but she would still call in sick for the week so that could take care of him. There was no telling what could happen to him in that course of a week.

There was once when a man actually broke into the apartment and tried to rape him, but his mother managed to get rid of him by threatening to call the police.

After all these years, Nagisa came to understand how much his mother did for him. Thus, he did not question his mother when she just broke down one day. Her mind had broken due to the strain of working too hard to bring up her only son. She began to have hallucinations, thinking that she had been raising a daughter instead of a son. She would scream and yell at him to get _better_ , so that he would not end up like her, a mother who had to get three jobs to feed the family. She would dress him up in pretty outfits.

Nagisa did not complain at all. His mother sacrificed a lot for him, so it was the least he can do for her.

His first year spent in Kunigigaoka High School was like any other normal school year. He made a few friends and hung out at the arcade. He made sure to abide by his mother's harsh rules and return home by four in the afternoon. He became fast friends with a red headed boy by the name of Akabane Karma, and spent most of his time in school with him.

That year, he had to call up the school himself to inform them that he was sick, and that he would not be attending classes for a week. His mother was in no right condition to call the school at all.

His second year spent in Kunigigaoka High School was rather sad. The Class A students started to take their disdain towards students from other classes up a notch. Due to his appearance, Nagisa was often bullied. To make things worse, his mother assumed that he was the one getting into fights and punished him instead. Thankfully, Karma would always step in when the bullying becomes worse.

That year was the second time he had to call up the school himself to inform them of his illness.

His final year spent in Kunigigaoka High School was really fun. The octopus who blew up the moon became his homeroom teacher, and his class turned into an assassination classroom. He honed his skills both as an assassin and as a student. For the first time in his life, he felt true happiness. That year was the same year that he harbored a crush on his red headed best friend. He hid his feelings from the boy, fearing rejection if he ever confessed.

When he called Karasuma-sensei to tell him that he was sick, the three teachers immediately offered to visit him to give him extra tutoring. He refused them politely, not wanting them to witness his mother in a deranged state. That week was the week he missed the assassination attempt where the class managed to reduced the octopus into his glass ball form yet again.

That week was the week he yelled out his best friend's name as he pleasured himself.

Nagisa really enjoyed his final year in high school. To add the cherry on top of the cake, his teachers somehow managed to cure his mother out of her hallucinations and she returned to the loving mother she used to be. After that, she would visit the therapist to set up appointments and get herself treatment, in hopes of becoming a better mother for him.

After graduating, Nagisa kept in contact with the students of Class 3-E. Since they bought the classroom in the mountains, they visited it every year. They would catch up with each other and have fun. Seven years have passed and Nagisa has finally achieved his goal to become a teacher. He now works as a homeroom teacher for Class 3-5 in Paradise High School. All in all, Nagisa can say that he lived a good life.

* * *

It was another day.

Nagisa woke up with a smile. He brushed his teeth, washed his face, did everything a normal person would do in a typical morning. He would be visiting the classroom in the mountains with the rest of his ex-classmates in a while, so he packed a bag with all the essential items that he would need for the day.

He felt the familiar sense of exhilaration as he made his way up the mountain, jumping from tree to tree. As he reached the wooden building, he noticed that most of his classmates were already there. Smiling, he ran up to them.

"Sorry I'm late!"

They looked up at his shout, grinning in return as they greeted him back.

Then they set to work. Splitting into several groups, they swept and mopped the floor, cleared the field, dusted the windows and arranged the tables. As they worked, they chatted happily to each other, laughing when the other said a joke.

It was like they were in their high school years again, having fun whilst learning.

As the sun started to set, the former classmates bade each other goodbye as they returned to their respective homes. They had to work the next day, but they promised each other to keep in contact. Nagisa, however, stayed behind as he stared at his old classroom with a wistful smile.

 _See, Koro-sensei? We've grown so much. Are you proud of the people we have become?_

He sat at his former seat, staring at the blackboard as reminisced of his school days. His vision began to blur as his body gave out to exhaustion.

* * *

Nagisa woke up the next morning with his whole body aching and an erection. He silently cursed. Of all days, his sickness decided to arrive on this day? The tealnette knew that he was in no condition to walk around, a single mis-step could send him rolling down the mountain, possibly to his death. Yet, there was no one he could rely on for help. His mother was in Italy for a trip so she was out of option.

Another round of pain coursed through his body as he jerked on the floor. He reached for his phone and tried to dial someone from his contacts. Someone, anyone would do. He needed to get back to his apartment.

 _"Hello?"_

"...help."

 _"Nagisa! What happened? Is there something wrong?"_

"... in Class 3-E."

There was a distinct sound of rustling from the other line.

 _"I'll be there soon. Hold on, okay?"_

Nagisa could feel himself losing consciousness. His body was aching so bad.

"Help."

 _"I am. I'm coming over right now. Keep talking to me."_

 _"Nagisa?"_

 _"Nagisa?! Answer me!"_

* * *

 **And that's it for this chapter! I hope you guys understand what is going on with the plot. Compared to my other fics, this is vastly different and hopefully I won't get any more smut ideas in the near future. Though the ideas were good, it was really embarrassing for me to write out things like that. While I have no problem with reading, I definitely have problems writing them. Anyways, I should stop rambling. Till then, ja~**

 **Yours,**

 **BlueSkyBlue,**

 **a.k.a. OtonashiHayuka**


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